usb: gadget: Call g_dnl_bind_fixup() before testing g_dnl_serial length

After the commit SHA1: 842778a091 - the serial number descriptor is only
visible when we have non zero length of g_dnl_serial.

However, on some platforms (e.g. Siemens) the serial number is set at
g_dnl_bind_fixup(), so with the current code we will always omit the
serial (since it is not set).

This commit moves the g_dnl_bind_fixup() call before the g_dnl_serial
length test.

Signed-off-by: Lukasz Majewski <lukma@denx.de>
Acked-by: Heiko Schocher <hs@denx.de>
Tested-by: Heiko Schocher <hs@denx.de>

drivers/usb/gadget/g_dnl.c

@@ -224,6 +224,8 @@ static int g_dnl_bind(struct usb_composite_dev *cdev)
 	g_dnl_string_defs[1].id = id;
 	device_desc.iProduct = id;
 
+	g_dnl_bind_fixup(&device_desc, cdev->driver->name);
+
 	if (strlen(g_dnl_serial)) {
 		id = usb_string_id(cdev);
 		if (id < 0)
@@ -233,7 +235,6 @@ static int g_dnl_bind(struct usb_composite_dev *cdev)
 		device_desc.iSerialNumber = id;
 	}
 
-	g_dnl_bind_fixup(&device_desc, cdev->driver->name);
 	ret = g_dnl_config_register(cdev);
 	if (ret)
 		goto error;